Pharmacognosy with Basics of Plant Biochemistry - Kovalyov V. M. 2004

Special Part
Lipids

It is rather difficult to define the term "lipid" because it does not refer to a distinct group of compounds with common structural features. Lipids are a group of Organic compounds—fats and fat-like substances—that are chemically heterogeneous yet share common physicochemical properties. Lipids are insoluble in Water and readily soluble in organic Solvents (such as ether, chloroform, acetone, hexane, and benzene).

There are three main classifications of lipids: chemical (structural), biological, and physicochemical. According to the biological Classification, lipids are divided into reserve and structural lipids. The physicochemical classification distinguishes between nonpolar (neutral) and polar lipids, as well as saponifiable (fats, Waxes, Complex Lipids) and nonsaponifiable lipids (Isoprenoids, carotenoids, Prostaglandins, etc.).

Based on their solubility and saponification characteristics, terpenoids, Steroids, carotenoids, and chlorophyll are also classified as lipids; however, these compounds are discussed in other sections of the textbook and are therefore omitted from this chapter. Below, we will focus exclusively on the group of lipids whose structures contain fatty acid residues: namely, free Fatty acids, fats (lipids proper), and fat-like substances (lipoids).